Pump



July 2, 1940.

F. w. DAVIS 2,206,079

PUMP

Filed July 28, 1936 s Sheets-Sheet 1 I INVENTOR nwvcls HZDAVI-S July 2, 1940. F. w. DAVIS 2,206,079

PUMP

Filed July 28, 1936 3 Sheets-Sheet 2 INVENTOR flwvcls w DAVIS W mRNEY;

3 Sheets-Sheet a mvrmok FRANCIS MDHVIS ATTORNEYS.

F. W. DAVIS PUMP Filed July 28, 1936 vaaanaum July 2, 194-0.

Patented July 2, 1940 UNITED STATES PUMP- Francis W. Davis, Belmont, Mass. Application July'28, 1936, Serial No. 93,034

I 2 Claims.

This invention relates to pumps, and more particularly to fluid pumps of the rotary gear type.

The principal object of the invention is to provide, in a rotary gear pump or in a pump of similar design or operation, novel details of construction which render the pump extremely economical of manufacture aswell as satisfactory of operation.

Other objects of the invention are to provide novel means for equalizing end thrust on the rotary gears or pumping elements, novel means for insuring force feed lubrication of the bearings of rotating. elements of the pump, and novel means for sealing a pump drive shaft to a pump 16 casing.

Still further objects of the invention will be readily apparent to those skilled in the art to which the invention appertains upon reference to the following detailed description of an emb0 iiment, chosen by way of example and disclosed in the appended drawings. In these drawings- Figure 1 is a vertical section, as if on the line I- -l of Figure 2.

Figure 2 is a horizontal section, as if on the line 22 of Figure 1.

Figure 3 is a partial vertical section, as if on the,

line 3-3 of Figure 1.

Figure 4 is'a side view, as if from the right of Figure 1, with parts cut away for purposes of clarity.

Figures 5'and 6 are details in section, as if on the lines 5-5 and 66 of Figures 3 and 4, respectively.

The pump shown inthe drawings includes a pump casing l0, having an open top providedwith a top ledge Illa and a tank H, mounted thereon and secured thereto byscrews l2.

- The pump casing includes a driving end section l4, a center section, l5, and a delivery end section I6, maintained in alinement by dowels l'l disposed in alined bores of the sections, the bores being closed by dowel plugs l8, and relatively se-.

cured by elongated cap screws IQ, of which there are eight shown. The sections may be joined toform a complete pump casing, now to be described in detail.

,In the lower and forward corner of the right side wall 20 of section l6 (Figure 4) is a hole 2| into which may be connected an inlet pipe, not

shown, the hole establishing communication between the inlet pipe and a cavity 22 which opens into cavities 23 and 24 of center section l5 (Figure 3).

into the inlet or low pressure side of the substantially oval pumpor gear chamber 26 through Cavity 24 of section IS in turn opens .a trumpet-shaped vertical inlet opening 21, the open sides of the chamber 26 and inlet 21 being closed by vertical webs 28 (Figure 1) formed as part of the end sections I4 and I6, these webs corresponding roughly in shape .to the shape of 5 the peripheral wall 29 of the gear chamber 26.

In one of those portions of the upper part of delivery end section l6 which connectaweb 28 to 'wall 20 is a horizontal bore 3! (Figure 1) which passes through web 28 and wall 20 and opens into the upper part of pump chamber 26 to form an outletthereof, and which has a threaded part 32 adjacent side wall 20, to receive an outlet pipe, not shown.

Disposed within gear chamber 26 dividing the 15 latter into a low pressure side (near inlet 21) and a high pressure side (near outlet bore 3|), are the pumping gears (Figure 3), of which there are a driving gear 34 and a driven gear 35, both having meshing helical teeth of the segmental form shown, it being understood that other suitable gear teeth may be provided, if desired. These gears pump fluid from the inlet 21 to the outlet bore 3|, in a manner well known to those acquainted with fluid pumps of the geared type.

The driving gear 34 is supported on and keyed to a driving gear shaft 36 and fits relatively closely, though without binding, between the side walls of chamber 26, namely webs 28. The driving shaft 36 (Figure 2) is joumaled in bearings 31, 31a and 38, press fitted into bores 39 and 40 of sec-' tions' l4 and I6, bearings 31 and 31a being'in the same bore and being relatively separated, as shown, by an annular space 4|.

One end of shaft 36 projects through a stuffing box onthe 'left side wall of section l4 to be connected to a driving device, such as amotor or the like, the stuffing box comprising a boss 42 projecting from the wall, suitable packing 43 therein; and a cover 44 threaded thereon.

The other end of thedriving shaft is counterbored, as at 46, to receive a thrust equalizing plug 41 provided with annular grooves 48 and a head 49, adjacent to the end of the bearing 38, the latter having a notch 50 in its end. The end of 45 the bearing 38 forms a shoulder around and beyond the end of the shaft 36. The head 49 of the plug 41 seats on said shoulder, restraining the plug from exerting any axial thrust on the shaft by contact with either the annular end face of 50 the shaft or the'inn'er end of the hollow. An end plug 5| threaded into a threaded enlargement 52 of bore 40 closes the latter.

- The driven gear 35 is supported and journaled on the driven gear shaft 54 and also fits relatively t closely, though without binding, between the side walls of chamber 26, namely, webs 28. The shaft 54 (Figure 2) is journaled in bearings 55 and 56 press fitted into bores 51 and 58 of sections M and 6. The driven shaft has an axial bore 59 therethrough and a counterbore 6| at its left end receiving a thrust equalizing plug 62 provided with annular grooves 63 and a head 64 adjacent to the end of the bearing 55, the latter having a notch 55a in its end. An end plug 65 threaded into a threaded enlargement 66 of bore 51 closes the latter. The enlargement 61 of bore 56 at the right end of the shaft 54 receives an end plug 68, which closes the bore 58.

Since the gears 34 and are helical, it is evident that the interfacial pressure of their contacting teeth will have components parallel to gear axes, these components resulting in an end thrust in one direction on one gear shaft and an equal and opposite end thrust on the other shaft. According to the present invention, means are provided to equalize or counteract these end thrusts. As shown in Figures 4 and 6, a duct 10 is provided connecting the high pressure side of the pump chamber, namely, the outlet bore 3|, to the space in bore and its enlargement 52 between the head 49 of the thrust equalizing plug and the end of the shaft 36.

Fluid under outlet pressure (high) acts on the annular end faceof the shaft 36 and exerts an endwise thrust on the driving shaft 36 towards the left. The plug 5| acts as an abutment for plug end 49 in one direction and the bushing 38 acts as an abutment for plug end 49 in the other direction.

A portion of the fluid will pass into the countel-bore 46 and the partial bore H of the shaft (Figures 2 and 6), and will pass to the left end of the driving shaft. This portion of thefluid will work its way through the transverse shaft relief ducts 13 in the left end of the shaft and into the annular space 4| between bushings 31, 31a, escaping from this space, through ducts 15 (Figure 1) to the low pressure side cavity 16 in section l4 connected to the low pressure side cavity 24 of section I5.

Connecting the high pressure side of the gear chamber, namely that part above the gears therein, to the space in bore 5'! and its enlargement 66 between the head 64 of thrust equalizing plug 62 and the end plug 65 are a bore 11 (Figures 3 and 5) and a. thrust equalizing duct 18.

Fluid under outlet pressure (high) works into the space between plug end 64 and the end of the shaft 54, thus exerting an endwise thrust on the driven shaft towards the right. The plug 65 and the bushing'55 act as abutments for the plug end 64, thus holding it in place.

A portion of the fluid will pass into the counterbore 6| and the bore 59 of the shaft and will pass to the right-hand end of the shaft. This portion will return to the low pressure side of the pump through a vertical'duct 19 (Figures 2 and 4), connecting bore 58 at the right-hand end of the shaft to the low pressure cavity 22.

It is evident that by reason of the axial bores in the shafts 36 and 54, each shaft has a plurality of axially spaced face areas facing in the direction of the impressed axial thrust so as to receive the thrust of liquid pressure opposed to the impressed axial thrust, the efiective components of such areas on each shaft equalling the crosssectional area of the shaft. High-pressure fluid is directed against some of these areas by connection with the discharge side of the pump, lowpressure fluid being directed against the others by connection with the suction side of the pump. By suitably proportioning the high-pressure and low-pressure areas, the proper equalizing thrusts on the shafts are obtained.

The shaft relief ducts 13, the space 4|, and the return ducts I5 create a fluid seal, on the lefthand end of the driving shaft, to prevent air from outside the pump casing passing into the pump housing through the space around the end of shaft 36. A certain amount of high pressure fluid will escape from the pump housing 26 between the shaft 36 and the bushing 31. However, this pressure fluid will flow to the low pressure chamber through the space 4| and ducts I5.

This seal will not, however, prevent the leakage of fluid from the low pressure side of the pump to the outside thereof, such escape being prevented by the packing 43. However, the packing is not subjected to the higher fluid pressure but only to the lower fluid pressure, the seal at 13, 4| and I5 isolating the gland from the high pressure side of the pump.

The circulation of fluid being pumped (often oil for lubrication purposes) through and around the bearings at both ends of the shafts insures a force feed lubrication of these parts.

Suitable oil sealing ducts, such as the vertical ducts (Figures 2 and 3) and the horizontal ducts 8| (Figures 1 and 3), are provided to form oil seals between the walls of the center section l5 and the adjacent walls of the end sections I4 and I6.

These ducts are always in communication with the low pressure side of the pump casing and thus form an oil seal entirely surrounding the pump. In this manner air is prevented from leaking into the pump chamber 26 under any and all conditions.

Air relief ducts 84 (Figures 2 and 4) are provided for relieving trapped air within the end casing 6. The trapped air can readily escape to the upper portion of the casing l6 and from there into the tank The tank ll, previously mentioned as being disposed upon the pump casing ID, has a normally open botten providing direct and unrestricted communication between the low pressure interior of the pump casing and the interior of the tank, and has a closed top provided with a filter type filler device, referenced generally at 9|, the same not being described in detail since it forms no part of the present invention.

The tank is also provided with a relief valve to relieve excessive pressures built up within the pump, the valve providing communication between the delivery or outlet side of the pump and the interior of the tank when the pump pressure becomes excessive. The relief valve (Figures 1 and 4) includes a valve seat ring 92 press fitted into a vertical bore 93 of the top Illa of pump section |6 to open communication getween the tank and the outlet bore 3|, as indicated. Adapted to seat upon and guided within the valve seat ring'is a valve proper 94 normally held against the upper beveled surface 66 of the seat by means of a spring pressed washer 91 engaging the top surface of the valve proper and adapted to be moved downwardly by the valve spring 96, enclosed within the bracket 99 secured to the top ledge Illa of the pump section 6 by means of bolts "H. A suitable adjusting screw, referenced generally at I02, is provided to determilne the adjustment and capacity of the relief va ve.

It will be observed that a pressure at the delivery or outlet end of the pump, in excess of that for which the valve spring is adjusted by the screw I02, will cause the valve proper 94 to move away from the seat vertically and permit escape of pumped fluid back to the low pressure interior of the tank ll.

In order to permit a gravity flow of fluid from the low pressure side of the pump casing to the outletbore 3l, when the pump is not working, the bore 11 (Figures 1 and 5) is provided with a port I08, connecting such bore to the interior of the pump casing outside of the pump chamber, that is to say, to the low pressure side of the pump. This port may be closed by a ball check I09 adapted to be forced against the port I" by the fluid pressure within the pump chamber when the pump is working. However, when the pump is not working, and no pressure exists in the pump chamber, the ball I08 will drop or roll to the right as far as permitted by the retaining pin Ill, sufficient to open the port I" and permit the flow of fluid by gravity from the tank H or from the interior of the pump casing into the pump chamber above the gears, and thence to the outlet 3|.

From the foregoing, it will be observed that there has been provided a fluid pump provided with suitable and satisfactory means for equalizing end thrust on the rotating pumping elements, means for insuring a force feed or pressure lubrication of the bearings of the rotating elements of the pump, means creating a high pressure fluid seal between the drive shaft and the casing, thus preventing leakage around the pump shaft, and

novel details of construction which make the within said chamber,

pump of the invention practical, economical of manufacture, and satisfactory of operation.

Now having described a preferred embodiment of the invention chosen by way of example, reference will be had to the following claims which determine the scope of the invention.

I claim: 1 1. In a fluid pressure pump, a casing having a chamber therein, a pair of rotating pumping-ele-.

ments in said chamber each normally subject to an axial reaction thrust from the other by mutual driving contact during operation and each having a shaft portion projecting into a wall of said casing in the direction of the axial thrust impressed thereon, and means for equalizing said thrusts by fluid pressure applied to said shaft portions only, said means comprising means for introducing fluid from the discharge side of the pump between the end of each said shaft portion and an adjacent portion of said housing and means for restricting the area of the shaft portion acted on by the pressure fluid to a predetermined fraction of its cross-sectional area.-

2. In a fluid pressure pump, a casing having a chamber therein, a pair of helical-pump gears one of said gears being driven solely by its engagement with the other, whereby axial reaction thrusts are impressed on said gears in opposite directions during operation of the pump, ,a hollow shaft extending from each said gear into the wall of said casing in the direction of axial thrust of its respective gear end, a plug fitted into the open end of each said hollow shaft, means for directing fluid pressure against the end area of each shaft surrounding the opening therein, and means connecting the interior of the shaft with the lowpressure site of said pump. Y

FRANCIS W. DAVIS.

and open at its 

